/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.naming;

import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NameParser;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;

/**
 * Catalina JNDI Context implementation.
 * 
 * @author Remy Maucherat
 * @version $Id: SelectorContext.java 939511 2010-04-29 23:48:20Z kkolinko $
 */

public class SelectorContext implements Context {

	// -------------------------------------------------------------- Constants

	/**
	 * Namespace URL.
	 */
	public static final String prefix = "java:";

	/**
	 * Namespace URL length.
	 */
	public static final int prefixLength = prefix.length();

	/**
	 * Initial context prefix.
	 */
	public static final String IC_PREFIX = "IC_";

	private static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
			.getLog(SelectorContext.class);

	// ----------------------------------------------------------- Constructors

	/**
	 * Builds a Catalina selector context using the given environment.
	 */
	public SelectorContext(Hashtable env) {
		this.env = env;
	}

	/**
	 * Builds a Catalina selector context using the given environment.
	 */
	public SelectorContext(Hashtable env, boolean initialContext) {
		this(env);
		this.initialContext = initialContext;
	}

	// ----------------------------------------------------- Instance Variables

	/**
	 * Environment.
	 */
	protected Hashtable env;

	/**
	 * The string manager for this package.
	 */
	protected StringManager sm = StringManager.getManager(Constants.Package);

	/**
	 * Request for an initial context.
	 */
	protected boolean initialContext = false;

	// --------------------------------------------------------- Public Methods

	// -------------------------------------------------------- Context Methods

	/**
	 * Retrieves the named object. If name is empty, returns a new instance of
	 * this context (which represents the same naming context as this context,
	 * but its environment may be modified independently and it may be accessed
	 * concurrently).
	 * 
	 * @param name
	 *            the name of the object to look up
	 * @return the object bound to name
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object lookup(Name name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingName", "lookup",
					name));
		}

		// Strip the URL header
		// Find the appropriate NamingContext according to the current bindings
		// Execute the lookup on that context
		return getBoundContext().lookup(parseName(name));
	}

	/**
	 * Retrieves the named object.
	 * 
	 * @param name
	 *            the name of the object to look up
	 * @return the object bound to name
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object lookup(String name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingString",
					"lookup", name));
		}

		// Strip the URL header
		// Find the appropriate NamingContext according to the current bindings
		// Execute the lookup on that context
		return getBoundContext().lookup(parseName(name));
	}

	/**
	 * Binds a name to an object. All intermediate contexts and the target
	 * context (that named by all but terminal atomic component of the name)
	 * must already exist.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @param obj
	 *            the object to bind; possibly null
	 * @exception NameAlreadyBoundException
	 *                if name is already bound
	 * @exception InvalidAttributesException
	 *                if object did not supply all mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void bind(Name name, Object obj) throws NamingException {
		getBoundContext().bind(parseName(name), obj);
	}

	/**
	 * Binds a name to an object.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @param obj
	 *            the object to bind; possibly null
	 * @exception NameAlreadyBoundException
	 *                if name is already bound
	 * @exception InvalidAttributesException
	 *                if object did not supply all mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void bind(String name, Object obj) throws NamingException {
		getBoundContext().bind(parseName(name), obj);
	}

	/**
	 * Binds a name to an object, overwriting any existing binding. All
	 * intermediate contexts and the target context (that named by all but
	 * terminal atomic component of the name) must already exist.
	 * <p>
	 * If the object is a DirContext, any existing attributes associated with
	 * the name are replaced with those of the object. Otherwise, any existing
	 * attributes associated with the name remain unchanged.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @param obj
	 *            the object to bind; possibly null
	 * @exception InvalidAttributesException
	 *                if object did not supply all mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void rebind(Name name, Object obj) throws NamingException {
		getBoundContext().rebind(parseName(name), obj);
	}

	/**
	 * Binds a name to an object, overwriting any existing binding.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @param obj
	 *            the object to bind; possibly null
	 * @exception InvalidAttributesException
	 *                if object did not supply all mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void rebind(String name, Object obj) throws NamingException {
		getBoundContext().rebind(parseName(name), obj);
	}

	/**
	 * Unbinds the named object. Removes the terminal atomic name in name from
	 * the target context--that named by all but the terminal atomic part of
	 * name.
	 * <p>
	 * This method is idempotent. It succeeds even if the terminal atomic name
	 * is not bound in the target context, but throws NameNotFoundException if
	 * any of the intermediate contexts do not exist.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @exception NameNotFoundException
	 *                if an intermediate context does not exist
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void unbind(Name name) throws NamingException {
		getBoundContext().unbind(parseName(name));
	}

	/**
	 * Unbinds the named object.
	 * 
	 * @param name
	 *            the name to bind; may not be empty
	 * @exception NameNotFoundException
	 *                if an intermediate context does not exist
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void unbind(String name) throws NamingException {
		getBoundContext().unbind(parseName(name));
	}

	/**
	 * Binds a new name to the object bound to an old name, and unbinds the old
	 * name. Both names are relative to this context. Any attributes associated
	 * with the old name become associated with the new name. Intermediate
	 * contexts of the old name are not changed.
	 * 
	 * @param oldName
	 *            the name of the existing binding; may not be empty
	 * @param newName
	 *            the name of the new binding; may not be empty
	 * @exception NameAlreadyBoundException
	 *                if newName is already bound
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void rename(Name oldName, Name newName) throws NamingException {
		getBoundContext().rename(parseName(oldName), parseName(newName));
	}

	/**
	 * Binds a new name to the object bound to an old name, and unbinds the old
	 * name.
	 * 
	 * @param oldName
	 *            the name of the existing binding; may not be empty
	 * @param newName
	 *            the name of the new binding; may not be empty
	 * @exception NameAlreadyBoundException
	 *                if newName is already bound
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void rename(String oldName, String newName) throws NamingException {
		getBoundContext().rename(parseName(oldName), parseName(newName));
	}

	/**
	 * Enumerates the names bound in the named context, along with the class
	 * names of objects bound to them. The contents of any subcontexts are not
	 * included.
	 * <p>
	 * If a binding is added to or removed from this context, its effect on an
	 * enumeration previously returned is undefined.
	 * 
	 * @param name
	 *            the name of the context to list
	 * @return an enumeration of the names and class names of the bindings in
	 *         this context. Each element of the enumeration is of type
	 *         NameClassPair.
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NamingEnumeration list(Name name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingName", "list",
					name));
		}

		return getBoundContext().list(parseName(name));
	}

	/**
	 * Enumerates the names bound in the named context, along with the class
	 * names of objects bound to them.
	 * 
	 * @param name
	 *            the name of the context to list
	 * @return an enumeration of the names and class names of the bindings in
	 *         this context. Each element of the enumeration is of type
	 *         NameClassPair.
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NamingEnumeration list(String name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingString", "list",
					name));
		}

		return getBoundContext().list(parseName(name));
	}

	/**
	 * Enumerates the names bound in the named context, along with the objects
	 * bound to them. The contents of any subcontexts are not included.
	 * <p>
	 * If a binding is added to or removed from this context, its effect on an
	 * enumeration previously returned is undefined.
	 * 
	 * @param name
	 *            the name of the context to list
	 * @return an enumeration of the bindings in this context. Each element of
	 *         the enumeration is of type Binding.
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NamingEnumeration listBindings(Name name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingName",
					"listBindings", name));
		}

		return getBoundContext().listBindings(parseName(name));
	}

	/**
	 * Enumerates the names bound in the named context, along with the objects
	 * bound to them.
	 * 
	 * @param name
	 *            the name of the context to list
	 * @return an enumeration of the bindings in this context. Each element of
	 *         the enumeration is of type Binding.
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NamingEnumeration listBindings(String name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingString",
					"listBindings", name));
		}

		return getBoundContext().listBindings(parseName(name));
	}

	/**
	 * Destroys the named context and removes it from the namespace. Any
	 * attributes associated with the name are also removed. Intermediate
	 * contexts are not destroyed.
	 * <p>
	 * This method is idempotent. It succeeds even if the terminal atomic name
	 * is not bound in the target context, but throws NameNotFoundException if
	 * any of the intermediate contexts do not exist.
	 * 
	 * In a federated naming system, a context from one naming system may be
	 * bound to a name in another. One can subsequently look up and perform
	 * operations on the foreign context using a composite name. However, an
	 * attempt destroy the context using this composite name will fail with
	 * NotContextException, because the foreign context is not a "subcontext" of
	 * the context in which it is bound. Instead, use unbind() to remove the
	 * binding of the foreign context. Destroying the foreign context requires
	 * that the destroySubcontext() be performed on a context from the foreign
	 * context's "native" naming system.
	 * 
	 * @param name
	 *            the name of the context to be destroyed; may not be empty
	 * @exception NameNotFoundException
	 *                if an intermediate context does not exist
	 * @exception NotContextException
	 *                if the name is bound but does not name a context, or does
	 *                not name a context of the appropriate type
	 */
	public void destroySubcontext(Name name) throws NamingException {
		getBoundContext().destroySubcontext(parseName(name));
	}

	/**
	 * Destroys the named context and removes it from the namespace.
	 * 
	 * @param name
	 *            the name of the context to be destroyed; may not be empty
	 * @exception NameNotFoundException
	 *                if an intermediate context does not exist
	 * @exception NotContextException
	 *                if the name is bound but does not name a context, or does
	 *                not name a context of the appropriate type
	 */
	public void destroySubcontext(String name) throws NamingException {
		getBoundContext().destroySubcontext(parseName(name));
	}

	/**
	 * Creates and binds a new context. Creates a new context with the given
	 * name and binds it in the target context (that named by all but terminal
	 * atomic component of the name). All intermediate contexts and the target
	 * context must already exist.
	 * 
	 * @param name
	 *            the name of the context to create; may not be empty
	 * @return the newly created context
	 * @exception NameAlreadyBoundException
	 *                if name is already bound
	 * @exception InvalidAttributesException
	 *                if creation of the subcontext requires specification of
	 *                mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Context createSubcontext(Name name) throws NamingException {
		return getBoundContext().createSubcontext(parseName(name));
	}

	/**
	 * Creates and binds a new context.
	 * 
	 * @param name
	 *            the name of the context to create; may not be empty
	 * @return the newly created context
	 * @exception NameAlreadyBoundException
	 *                if name is already bound
	 * @exception InvalidAttributesException
	 *                if creation of the subcontext requires specification of
	 *                mandatory attributes
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Context createSubcontext(String name) throws NamingException {
		return getBoundContext().createSubcontext(parseName(name));
	}

	/**
	 * Retrieves the named object, following links except for the terminal
	 * atomic component of the name. If the object bound to name is not a link,
	 * returns the object itself.
	 * 
	 * @param name
	 *            the name of the object to look up
	 * @return the object bound to name, not following the terminal link (if
	 *         any).
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object lookupLink(Name name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingName",
					"lookupLink", name));
		}

		return getBoundContext().lookupLink(parseName(name));
	}

	/**
	 * Retrieves the named object, following links except for the terminal
	 * atomic component of the name.
	 * 
	 * @param name
	 *            the name of the object to look up
	 * @return the object bound to name, not following the terminal link (if
	 *         any).
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object lookupLink(String name) throws NamingException {

		if (log.isDebugEnabled()) {
			log.debug(sm.getString("selectorContext.methodUsingString",
					"lookupLink", name));
		}

		return getBoundContext().lookupLink(parseName(name));
	}

	/**
	 * Retrieves the parser associated with the named context. In a federation
	 * of namespaces, different naming systems will parse names differently.
	 * This method allows an application to get a parser for parsing names into
	 * their atomic components using the naming convention of a particular
	 * naming system. Within any single naming system, NameParser objects
	 * returned by this method must be equal (using the equals() test).
	 * 
	 * @param name
	 *            the name of the context from which to get the parser
	 * @return a name parser that can parse compound names into their atomic
	 *         components
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NameParser getNameParser(Name name) throws NamingException {
		return getBoundContext().getNameParser(parseName(name));
	}

	/**
	 * Retrieves the parser associated with the named context.
	 * 
	 * @param name
	 *            the name of the context from which to get the parser
	 * @return a name parser that can parse compound names into their atomic
	 *         components
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public NameParser getNameParser(String name) throws NamingException {
		return getBoundContext().getNameParser(parseName(name));
	}

	/**
	 * Composes the name of this context with a name relative to this context.
	 * <p>
	 * Given a name (name) relative to this context, and the name (prefix) of
	 * this context relative to one of its ancestors, this method returns the
	 * composition of the two names using the syntax appropriate for the naming
	 * system(s) involved. That is, if name names an object relative to this
	 * context, the result is the name of the same object, but relative to the
	 * ancestor context. None of the names may be null.
	 * 
	 * @param name
	 *            a name relative to this context
	 * @param prefix
	 *            the name of this context relative to one of its ancestors
	 * @return the composition of prefix and name
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Name composeName(Name name, Name prefix) throws NamingException {
		prefix = (Name) prefix.clone();
		return prefix.addAll(name);
	}

	/**
	 * Composes the name of this context with a name relative to this context.
	 * 
	 * @param name
	 *            a name relative to this context
	 * @param prefix
	 *            the name of this context relative to one of its ancestors
	 * @return the composition of prefix and name
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public String composeName(String name, String prefix)
			throws NamingException {
		return prefix + "/" + name;
	}

	/**
	 * Adds a new environment property to the environment of this context. If
	 * the property already exists, its value is overwritten.
	 * 
	 * @param propName
	 *            the name of the environment property to add; may not be null
	 * @param propVal
	 *            the value of the property to add; may not be null
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object addToEnvironment(String propName, Object propVal)
			throws NamingException {
		return getBoundContext().addToEnvironment(propName, propVal);
	}

	/**
	 * Removes an environment property from the environment of this context.
	 * 
	 * @param propName
	 *            the name of the environment property to remove; may not be
	 *            null
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Object removeFromEnvironment(String propName) throws NamingException {
		return getBoundContext().removeFromEnvironment(propName);
	}

	/**
	 * Retrieves the environment in effect for this context. See class
	 * description for more details on environment properties. The caller should
	 * not make any changes to the object returned: their effect on the context
	 * is undefined. The environment of this context may be changed using
	 * addToEnvironment() and removeFromEnvironment().
	 * 
	 * @return the environment of this context; never null
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public Hashtable getEnvironment() throws NamingException {
		return getBoundContext().getEnvironment();
	}

	/**
	 * Closes this context. This method releases this context's resources
	 * immediately, instead of waiting for them to be released automatically by
	 * the garbage collector. This method is idempotent: invoking it on a
	 * context that has already been closed has no effect. Invoking any other
	 * method on a closed context is not allowed, and results in undefined
	 * behaviour.
	 * 
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public void close() throws NamingException {
		getBoundContext().close();
	}

	/**
	 * Retrieves the full name of this context within its own namespace.
	 * <p>
	 * Many naming services have a notion of a "full name" for objects in their
	 * respective namespaces. For example, an LDAP entry has a distinguished
	 * name, and a DNS record has a fully qualified name. This method allows the
	 * client application to retrieve this name. The string returned by this
	 * method is not a JNDI composite name and should not be passed directly to
	 * context methods. In naming systems for which the notion of full name does
	 * not make sense, OperationNotSupportedException is thrown.
	 * 
	 * @return this context's name in its own namespace; never null
	 * @exception OperationNotSupportedException
	 *                if the naming system does not have the notion of a full
	 *                name
	 * @exception NamingException
	 *                if a naming exception is encountered
	 */
	public String getNameInNamespace() throws NamingException {
		return prefix;
	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Get the bound context.
	 */
	protected Context getBoundContext() throws NamingException {

		if (initialContext) {
			String ICName = IC_PREFIX;
			if (ContextBindings.isThreadBound()) {
				ICName += ContextBindings.getThreadName();
			} else if (ContextBindings.isClassLoaderBound()) {
				ICName += ContextBindings.getClassLoaderName();
			}
			Context initialContext = ContextBindings.getContext(ICName);
			if (initialContext == null) {
				// Allocating a new context and binding it to the appropriate
				// name
				initialContext = new NamingContext(env, ICName);
				ContextBindings.bindContext(ICName, initialContext);
			}
			return initialContext;
		} else {
			if (ContextBindings.isThreadBound()) {
				return ContextBindings.getThread();
			} else {
				return ContextBindings.getClassLoader();
			}
		}

	}

	/**
	 * Strips the URL header.
	 * 
	 * @return the parsed name
	 * @exception NamingException
	 *                if there is no "java:" header or if no naming context has
	 *                been bound to this thread
	 */
	protected String parseName(String name) throws NamingException {

		if ((!initialContext) && (name.startsWith(prefix))) {
			return (name.substring(prefixLength));
		} else {
			if (initialContext) {
				return (name);
			} else {
				throw new NamingException(sm
						.getString("selectorContext.noJavaUrl"));
			}
		}

	}

	/**
	 * Strips the URL header.
	 * 
	 * @return the parsed name
	 * @exception NamingException
	 *                if there is no "java:" header or if no naming context has
	 *                been bound to this thread
	 */
	protected Name parseName(Name name) throws NamingException {

		if ((!initialContext) && (!name.isEmpty())
				&& (name.get(0).equals(prefix))) {
			return (name.getSuffix(1));
		} else {
			if (initialContext) {
				return (name);
			} else {
				throw new NamingException(sm
						.getString("selectorContext.noJavaUrl"));
			}
		}

	}

}
